How has the universe changed since last year?

All around, the universe is forever changing with each passing year.

This chapter presents the different regions of the Sun’s surface and interior, including the core, which is the only site where nuclear fusion occurs. With the passage of time and the consumption of hydrogen, the helium-containing region in the core expands and the maximum temperature increases, causing the sun’s energy output to increase.

(Credit: Wikimedia Commons/KelvinSong)

Our sun, from internal nuclear reactions, loses ~1017 kilograms of mass per year.

The Earth revolves around the Sun not in a perfect circle, but in an ellipse. The eccentricity, or the difference between the “long axis” and the “short axis” of our orbit, changes over time, while the orbital period between Earth and the sun, which defines our year, changes slowly over the life of our solar system. As the Sun loses mass via E=mc^2, the Earth slowly rotates outward, increasing its orbital distance by about 1.5 cm per year.

(Credit: NASA/JPL-Caltech)

Consequently, the Earth spirals outward, increasing our orbital radius by 1.5 cm (0.6 in) per year.

Earth’s rotation as seen from NASA’s MESSENGER spacecraft as it departed near our planet. Although the Earth’s rotation rate may appear to be constant, the length of the day is slowly lengthening due to the gravitational interactions between the Earth, the Moon, and the Sun.

(Credit: NASA/MESSENGER)

gravitational interactions slow our planet’s rotation; a day 14 microseconds longer than last year.

When the moon passes directly between the earth and the sun, a solar eclipse occurs. Whether the eclipse is total or annular depends on whether the angular diameter of the Moon appears larger or smaller than the Sun as seen from the Earth’s surface. Only when the Moon’s angular diameter appears to be greater than that of the Sun can a total solar eclipse occur.

(Credit: Kevin M. Gill/Flickr)

The distance between the Moon and Earth is lengthening by 3.8 cm (1.5 in) per year, making total solar eclipses rarer and shorter.

Changes in the luminosity and temperature of a star of one solar mass over the course of its life, from the beginning of nuclear fusion in its core 4.56 billion years ago until its transformation into a full red giant several billion years from now, which is the beginning of the end for sun-like stars. Although the annual changes are small, their cumulative effects cannot be ignored for a long time.

(Credit: RJHall/Wikimedia Commons)

Stellar evolution causes our Sun to heat up, becoming 0.0000005% brighter each year.

This small region near the core of NGC 2014 displays a mixture of evaporating gas globules and free-floating Puck globules, as dust moves from languid hot filaments above to denser, cooler clouds as new stars form in the interior below. The color combination reflects a difference in temperature and emission lines from different atomic signatures.

(Credit: NASA, ESA, and STScI)

Across the Milky Way, about 5 new low-mass stars formed last year.

When a star-forming region becomes so large that it spans an entire galaxy, that galaxy becomes a star galaxy. Here, Henize 2-10 is shown evolving towards that state, with young stars in many locations and active stellar nurseries in many locations across the galaxy. The majority of new stars in the universe are currently forming in large galactic bursts, although such events are becoming rarer and rarer.

(Credit: NASA, ESA, Zachary Schutte (XGI) and Amy Reines (XGI); Processing: Alyssa Pagan (STScI))

This is less than 0.0000001% of the 45 billion solar masses of new stars that are formed annually throughout the visible universe.

This illustration of bright supernova SN 1000+0216, the most distant supernova ever observed at a redshift of z = 3.90, since the universe was only 1.6 billion years old, is the current distance record holder for an individual supernova. At least 50 million new supernovae are expected to occur, universe-wide, each year.

(Credit: Adrian Malec and Marie Martig (Swinburne University))

Nearly 50 million new supernovae occurred within the visible universe last year.

temperature of the universe

At any point in our cosmic history, any observer will experience a regular “bath” of multidirectional radiation that originated back in the Big Bang. Today, from our vantage point, it is only 2.725 K above absolute zero, and thus is observed as a cosmic wave background, peaking at microwave frequencies. At large cosmic distances, when we look back in time, that temperature was hotter depending on the redshift of the observed distant object. As the new year rolls around, the CMB cools by about 0.2 nanokelvins more.

(Credit: Earth: NASA/BlueEarth; Milky Way: ESO/S. Brunier; CMB: NASA/WMAP)

The leftover glow from the Big Bang – the cosmic microwave background – is 200 pK cooler than it was a year ago.

The visible universe may be 46 billion light-years away in all directions from our vantage point, but there is certainly more to the unobserved universe, perhaps even an infinite amount, just like ours beyond. Over time, we will be able to see more of them, eventually revealing approximately 2.3 times as many galaxies as we can currently see. Even for the parts we never see, there are things we want to know about them. Gathering as much information as possible is vital towards this endeavour.

(Credit: Frederic Michel and Andrew Z. Colvin/Wikimedia Commons; annotations by E. Siegel)

Our cosmic horizon, which limits what we can see, is growing annually by 60 trillion km: 6.5 light-years.

Artist’s logarithmic scale concept of the visible universe. The solar system gives way to the Milky Way, which gives way to nearby galaxies which then give way to the massive structure and hot, dense plasma of the Big Bang on the outskirts. Every line of sight we can observe contains all of these epochs, but the search for the most distant object observed will not be complete until we map the entire universe. With each new year, a few tens of thousands of galaxies will likely become visible.

(Credit: Pablo Carlos Budassi)

The number of observable galaxies is also growing: by about 35,000 annually.

It is not accessible

The size of our visible universe (yellow), along with how much we could reach (purple) if we left today on a journey at the speed of light. The boundary of the visible universe is 46.1 billion light-years away, and this is the maximum distance from which a light-emitting object will reach us today after expanding away from us for 13.8 billion years. Anything that happens now within a radius of 18 billion light years will reach us and affect us; Nothing will happen beyond this point. Every year, another 20 million stars cross the threshold from being reachable to unreachable.

(Credit: Andrew Z. Colvin and Frederic Michel, Wikimedia Commons; Annotations: E. Siegel)

But fewer stars can be reached; This number decreases by about 20 million per year.

Perhaps surprisingly, this image shows stars in the halo of the Andromeda Galaxy. The brightest star with diffraction spikes is from within our Milky Way galaxy, while the individual points of visible light are mostly stars in our neighboring galaxy: Andromeda. Beyond that, however, a variety of faint smudges, galaxies in their own right, lurk beyond. Individual stars can be resolved into galaxies tens of millions of light-years across, but that only accounts for one galaxy in every billion. For 94% of the galaxies out there, we can’t reach their stars, even if we left today and headed toward them at the speed of light.

(Credit: NASA, ESA, and TM Brown (STScI))

Every year, the universe changes accumulating, changing our universe forever.

This annotated and rotated image of the JADES, Advanced Deep Extragalactic Survey JWST, shows the new cosmological record holder for the farthest galaxy: JADES-GS-z13-0, whose light comes to us from a redshift of z=13.2 and a time when the universe was 320 million years old. Just. Although we see galaxies farther away than ever before, we will never be able to reach them, even if we leave today at the speed of light.

(Credit: NASA, ESA, CSA, M. Zamani (ESA/Webb); science credits: Brant Robertson (UC Santa Cruz), S. Tacchella (Cambridge), E. Curtis-Lake (UOH), S. Normale Superiore) JADES Collaboration; Caption: E. Siegel)

Mostly Mute Monday tells an astronomical story with pictures and visuals and no more than 200 words. taciturn; smile more.

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